This invention relates to radiation beam position and more particularly to he plane at which a radiation beam is focused.
Heretofore focus spot determination for an infrared laser beam has been to direct the beam onto a piece of asbestos or plastic material and then noting the burn area. Movement of the plastic material to the plane at which the greatest burn intensity occurs determines the focal point of the beam. These techniques are time-consuming, inaccurate and involve a great deal of guess work.